ICL 4.8: Congenital Heart Disease Anatomy & Clinical Syndromes Flashcards
what is a congenital heart defect?
congenital heart defects are structural abnormalities present at birth that MAY result in alteration of heart function
what is the mechanism behind congenital heart defects?
faulty embryonic development:
- misplaced structures (TGA)
the aorta and pulmonary artery don’t always twist and they form transpositional great arteries where the aorta is connected to the right ventricle and pulmonary trunk is connected to the left ventricle
- arrest in the progression of a normal structure from an early stage to a more advanced one (ASD)
if the septum secundum doesn’t develop you’ll get an atrial septal defect
what is the etiology of congenital heart defects?
- single gene defect
- environmental factors
- viral exposure
- maternal ingestion of toxic substances
- unknown
viral exposure to which virus can cause a patent ductus arteriosus?
rubella
what is the most common congenital defect?
ventricular septal defect
least common is tricuspid atresia
what are the common features of congenital heart defects?
- history of early onset of cardiac symptoms such as birth (blue baby)
- loud murmur with a thrill along the left sternal border
- cyanosis with intense dyspnea on exertion early in childhood
- failure of normal growth and development
- rapid heart rate (160 to 180 beats per minute)
- pulmonary wheezing
what is cyanosis?
cyanosis results when the blood contains more than 5 grams of reduced hemoglobin/100 mL
cyanosis is recognizable by a purplish to bluish tinge to the skin in areas with dense superficial capillary circulation like the nails and lips
cyanosis is a common features of congenital heart defect
which congenital heart defects are associated with cyanosis?
- transposition of the great vessels
- tetralogy of fallot
- tricuspid atresia
- severe septal defect
- severe pulmonic stenosis
how are congenital heart defects classified?
Maude Abbott grouped cases in three categories according to the presence or absence of cyanosis
another more contemporary classification divides the cases into groups according to the presence and absence of a shunt
what is cyanose tardive?
initial left to right shunt with late reversal of the flow
so it used to be acyanotic but now it’s cyanotic
which congenital heart defects are associated with an initial left to right shunt?
- ventricular septal defect
- atrial septal defect
- patent ductus arteriosus
- persistent truncus arteriosus
which congenital heart defects are associated with an initial right to left shunt?
tetralogy of fallout
which congenital heart defects are associated with no shunt?
- transposition of the great vessels
- coarctation of the aorta
- pulmonary stenosis
- aortic stenosis
what is a VSD?
VSD = ventricular septal defect
it’s an abnormal opening in the ventricular septum that occur as an isolated lesion, or in combination with other congenital heart anomalies
VSD is a consequence of a failure of the interventricular septum to form
it is a common defect (30% of congenital heart diseases) with an incidence of 0.1% - 0.2% in the general population
what are the 2 types of VSDs?
- membranous VSD
- muscular VSD (less common)
VSDs may occur anywhere along the interventricular septum, but are most commonly located in the membranous portion of septum
how does the BP, O2 saturation and mean pressure change in a heart with a VSD?
blood will flow from the left to right ventricle so there will be reduced pressure in the LV
that also means that there will be increased oxygen saturation in the RV since oxygenated blood from the LV is flowing into it
what is an ASD?
ASD = atrial septal defect
ASD is an opening in the atrial septum caused by excessive resorption around the foramen secundum or hypoplastic growth of septum secundum (it’s too short)
it can occur anywhere along the the atrial septum, but the most common site is the midportion of the interatrial septum, in the region of the fossa ovale, termed an ostium secundum ASD
5-10% of congenital heart diseases; M/F = 1:2
what are the 3 types of ASD?
- ostium secundum defect (most common)
the septum secundum is mostly gone and blood just flows from the LA to RA through the ostium secundum
- ostium primum defect
septum premium doesn’t develop and blood flows through the foramen ovale
- sinus venosus defect
there’s just a hole at the top of what’s supposed to be the atrial septum
what are the symptoms and PE findings of someone with an ASD?
most infants are asymptomatic
it’s detected by a murmur when the kids become school-age
most common symptom in adult is the development of palpitations
prominent systolic impulse may be palpated along the lower left sternal border
asystolic murmur may be present
mid-diastolic murmur may also be present at the lower left sternal border
what is a PDA?
PDA = patent ductus arteriosus
PDA results when the Ductus Arteriosus fails to close after birth
the result is a persistent connection between aorta and pulmonary trunk
it can be life-threatening or life saving! –> if you have a PDA that’s really large so the shunt from the aorta to the pulmonary trunk decreases the blood going to the lungs which isn’t good –> however, if you have both a PDA and also happen to have transposition of the great vessels then the circulation is mixed and the only thing keeping the baby alive is the PDA
M:F = 1:3
frequently associated with maternal rubella infection during early pregnancy
how does the ductus arteriosus close normally?
when the baby is born and the lungs start working, they release bradykinin and allow for high O2 levels which both cause the ductus arteriosus to constrict and close
what medication do you give to close a PDA?
indomethacin!
it helps close the ductus arteriosus
what medication do you give to keep a PDA open?
prostaglandin
what is a CoA?
CoA = coarctation of aorta
coarctation is a pathologic narrowing of the aortic lumen that can occur anywhere along its length
M:F 2:1
what are the 2 types of coarctations of the aorta?
based on the location of the ductus arteriosus:
- PREDUCTAL
occurs when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart and aortic isthmus, resulting in hypoplastic development of the aorta - POSTDUCTAL
develops postnatally. It is most likely the result of muscular ductus arteriosus tissue extending into the aorta during fetal life; when ductal tissue constricts following birth, the ectopic tissue within the aorta also constrict, creating a “napkin ringlike” obstruction in the aorta
it is most commonly observed distal to the left subclavian artery, in the region near the ductus arteriosus
what are the symptoms of preductal coarctation of the aorta?
- congestive heart failure shortly after birth
- HTN in upper extremities and pressure reduced in lower extremities
- there’s differential cyanosis if the dustus arterosus remains open –> upper half of the body is perfused with oxygen while the lower half appears cyanotic
if the ductus arteriosus is open, as the aorta constricts the pressure will drop so then the pressure in the pulmonary is higher and deoxygenated blood from the pulmonary trunk will flow into the aorta causing cyanosis
preductal CoA occurs when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart and aortic isthmus, resulting in hypoplastic development of the aorta
what are the symptoms of postductal coarctation of the aorta?
in the majority of newborns, the obstruction is not severe and these patients grow and mature normally
if defect is severe the newborn develop congestive heart failure from pressure overload –> if the ductus is open then most of the blood going through the aorta will go to the pulmonary trunk which increases the amount of blood going to the lungs and the LV is going to have to push really hard to get all that blood there and that’s how you get pressure overload
within the first weeks of life the infants present with tachypnea, dyspnea, tachycardia and hepatomegaly
what is tetralogy of fallot?
The Tetralogy of Fallot is characterized
by a group of cardiac malformations
that result from a single defect: an abnormal anterosuperior and rightward displacement of the infundibular septum, resulting in an unequal division of the bulbus cordis into pulmonary and aortic outflow tracts
basically the aorta gets too greedy and loops a little extra so that it invades the space of the pulmonary trunk which reduces the size of the pulmonary trunk
this is the only congenital heart defect with a right to left shunt because the hypertrophy of the right ventricle increases pressure plus a VSD means blood is getting shunted from the RV to LV
what are the 4 anomalies associated with tetralogy of fallot?
- ventricular septal defect due to septum misalignment
- subvalvular pulmonic stenosis because of obstruction of the infundibular septum
- an overriding (dextroposed) aorta receives blood from both ventricles
- right ventricular hypertrophy due to the high pressure load of the pulmonic stenosis
PROV = pulmonic stenosis, RV hypertrophy, overarching aorta, VSD
slide 36
what are the symptoms of tetralogy of fallot?
- dyspnea on exertion or when crying –> because it increases the pressure in the hypertrophic RV
- “Tet spells” may occur following exertion or feeding
- convulsions due to cerebral hypoxemia
- children alleviate symptoms by “squatting”
- children with moderate pulmonary stenosis are often mildly cyanotic
- children with severe pulmonary stenosis present cyanosis in the first days of life
- systolic murmur heard best at the left upper sternal border
what is TGA?
TGA = transposition of the great arteries
TGA is present when the great vessels inappropriately arise from the opposite ventricle, that is, the aorta originates from the right ventricle and the pulmonary artery originates from the left ventricle
precise cause remains unknown; it may result of failure of the aorticopulmonary septum to spiral in a normal fashion during heart development
recently it has been suggested that the defect may be a result of abnormal growth and absorption of the subpulmonary and subaortic infundibuli during the division of the truncus arteriosus
what could save a baby from dying if they have TGA?
if they also have a VSD and ASD it’ll help sort of restore normal circulation
what is PTA?
PTA = persistent truncus arterosus
PTA is a congenital cardiac defect that can be explained as the result of absent or incomplete partitioning of the truncus arteriosus by the spiral septum, thus leaving a common trunk for the origin of the aorta, pulmonary arteries, and coronary arteries
basically it’s a neural crest defect because the neural crest didn’t seed the septum to form the aorta and pulmonary trunk so they just share a common trunk and blood from both the LV and RV flows into the common trunk and the degree of cyanosis just depends on the position of the trunk and how big it is
there are several variants of truncus arteriosus –> type 1 is the most common variant and consists of a single trunk that gives rise to a common pulmonary artery and ascending aorta
